One of the most difficult problems encountered in providing and maintaining litter boxes for cats to use indoors is the suppression of the odor from the cat's waste. Various preparations are sold in small containers which can be used by adding them from time to time to the litter material in the box as the litter material is used by the cat. The practice is not only inconvenient, but is also often messy and unpleasant, and it is difficult to obtain distribution of the odor suppressant where it will be most effectively utilized. If the odor suppressant is carefully mixed with the litter to obtain good distribution, the separate suppressant can be effective; however, usually some portions of the litter receive an excessive amount of the suppressant, resulting in a waste of the relatively expensive preparation, and other portions receive amounts too small to be effective. Hence, the use of a separate odor suppressant for addition to the litter material in the foregoing manner has not been generally accepted by cat owners. Another practice which has been successful in obtaining the desired suppression of the odor in the litter has been the mixing of the suppressant fully with litter at the time the litter is prepared and packaged for distribution and sale. After using the litter in the box, the cat customarily covers the waste by scraping the litter over the waste, using its paw to move the litter in the close proximity of the waste. Since the cat usually uses the litter only close to the center of the box near the top of the litter, only a small portion of the litter is used by the cat, the litter in the bottom and/or along the periphery of the box often remaining relatively clean and free of odor-causing waste. Since effective odor suppressants are generally rather expensive, the mixing of the suppressant with the litter before packaging unnecessarily increases the cost of the final material, in that a substantial amount of the litter material is never in contact with the cat's waste, and hence performs no appreciable function in suppressing the odor at any time during the use of the litter material.